My 06 wrx did same thing when I bought it from Audi. They sent it to osb park Subaru as they had no idea about wrx's abd the head mechanic said it was noisy and they made some adjustments. It hasn't done the click, power down and Woosh effect since. I can slightly here the compressor engage but that's all. But I can't remember exactly what it was they did. Buy maybe go there if it's close and ask....